对非均相串联催化体系进行机理研究对于理解和提高催化剂活性和选择性至关重要,但仍然具有挑战性。在这里,我们证明了对多步反应的深入机理研究可以指导我们利用可容易获得的前体来控制选择性合成苯基四氢喹啉或苯基喹啉。一锅生产可以通过定义明确的,由双功能金属-有机骨架支撑的Pd纳米颗粒催化而实现,仅水作为副产物。我们的机理研究从27.6 bar H 2下的操作魔术角旋转核磁共振研究确定了六个瞬态中间体和十个转变步骤。特别是,使用常规色谱技术无法观察到反应性中间体2-苯基-3,4-二氢喹啉,但发现在操作条件下其最高浓度为0.11 mol L –1。根据反应物种的动力学信息进一步推断出最可能的反应网络,该信息是从操作和非现场获得的反应研究。对复杂反应网络的深入了解使得能够通过添加均相助催化剂来动力学控制关键中间体2-苯基-3,4-二氢喹啉的转化,从而根据需要选择性生产四氢喹啉或喹啉。这项工作中证明的方法为
Strong Lewis acid air-stable cationic titanocene perfluoroalkyl(aryl)sulfonate complexes as highly efficient and recyclable catalysts for C–C bond forming reactions
A series of titanocene perfluoroalkyl(aryl)sulfonate complexes were synthesized, characterized, and applied in various C–C bond forming reactions.
一系列的钛ocene基过氟烷基(芳基)磺酸盐配合物被合成、表征,并应用于各种C-C键形成反应。
A novel simple bifunctional catalyst for the direct aldol reaction
作者:Chang Lu Liu、Hao Zhang、Ning Wang
DOI:10.1016/j.cclet.2010.12.025
日期:2011.6
Abstract Directaldolreactions of aldehydes and ketones can proceed smoothly in the presence of a catalytic amount of naphthol/sodium naphtholate (5 mol%) to afford the corresponding products with yields up to 98%. Such a bifunctional catalyst is more moderate than strong acid or base employed in directaldolreactions.
removal of the coordinated water, has been characterized by thermo-gravimetric analysis, IR, elemental analysis and variable temperature powder X-ray diffraction. Both 1 and its dehydrated species 1a catalyze the Claisen–Schmidt reaction under heterogeneous conditions, but 1a is a more effective catalyst under environmentally friendly conditions. The catalyst can readily be recovered and reused in successive
s with Zn/NH4Cl gave the corresponding quinoline N‐oxides in 80–90% yields. The reaction initiated the reduction of nitro group to afford the corresponding hydroxylamine, which intramolecularly condensed and followed by dehydration to give quinoline N‐oxide. Although treatment of 2‐nitrochalcone with Zn/NH4Cl in EtOH/H2O resulted in the formation of quinoline N‐oxide in low yield, the reaction of 2‐nitrochalcone
A magnesium-based multifunctional metal–organic framework: synthesis, thermally induced structural variation, selective gas adsorption, photoluminescence and heterogeneous catalytic study
layered alkaline earth metal–organicframework (MOF) compound, [Mg2(HL)2(H2O)4]·H2O}n (1) (H3L = pyrazole-3,5-dicarboxylate). Compound 1 selectively adsorbs hydrogen (H2) (ca. 0.56 wt% at 77 K) over nitrogen at 1 atm and demonstrates a strong blue fluorescent emission band at 480 nm (λmax) upon excitation at 270 nm. Notably, the 2D framework compound efficiently catalyzes the aldol condensation reactions
通过依赖温度的合成制备了三种基于镁的羧酸盐骨架体系。通过水热法合成化合物,并通过单晶X射线衍射分析表征。介质温度的逐步升高导致网络尺寸的逐步升高,最终导致形成新的二维二维层状碱土金属-有机骨架(MOF)化合物[Mg 2(HL)2( H 2 O)4 ]·H 2 O} n(1)(H 3 L =吡唑-3,5-二羧酸酯)。化合物1选择性吸附氢(H 2)(ca。在1个大气压77 K)在氮0.56%(重量)和在480nm处(演示了强的蓝色荧光发射带λ最大在270nm处)激发时。值得注意的是,在环境友好的条件下,二维骨架化合物可有效催化异质介质中各种芳香醛与酮的醛醇缩合反应。催化剂可以循环使用几次,而活性没有任何重大损失。